TW201038125A - Organic light-emitting diode and method of manufacturing the same - Google Patents

Abstract

An organic light emitting diode (OLED) including: a substrate; a reflection layer on the substrate and including metal; a first electrode on the reflection layer and including a light transparent aluminum zinc oxide (AZO); an organic layer on the first electrode and including an emitting layer; and a second electrode on the organic layer and including a semi-permeable reflection layer.

Description

201038125 VI. Description of invention: [Cross-reference to related patent application] This application claims the priority and right of the Korean special application for the Korean Intellectual Property Office on February 17, 2009 (4) 1G_2_Sale 3126 system, the patent application The entire content of this article is used in this article. TECHNICAL FIELD OF THE INVENTION The present invention relates to an organic light emitting diode (〇LED) and preparation thereof

〇 [Prior Art] An organic light-emitting diode (〇LED) is prepared by sequentially stacking a first electrode as an anode, an organic emission layer, and a second electrode as a cathode. In the top (four) OLED structure in which light emitted from the organic emission layer is transmitted through the second electrode to obtain a image, a first electrode is formed on the reflective layer using a metal oxide having a high work function, and a semi-transparent reflective electrode is used. A second electrode is formed. Further, the luminous efficiency of light emitted to the second electrode in the top emission type OLED can be further improved by the resonance between the reflective layer and the second electrode. ^In this case, if the thickness of the first electrode of the anode is increased, the y g point can be formed and the power consumption can be reduced. Further, in the top emission type OLED wafer, the organic emission layer is transmitted through the anode due to resonance between the reflective layer formed under the anode and the semipermeable reflective layer serving as the cathode. Since the absorption constant k of the anode of A and ^ increases, the luminous efficiency decreases. In the conventional OLED, the indium tin oxide used as the anode (the ιτ(1) layer has a high absorption constant k of 201038125, and the etching rate is different from the etching rate of the reflective layer, and thus it is difficult to use it to form a thick anode. [Invention] One aspect of one specific embodiment relates to an organic light-emitting diode (OLED) having improved (or excellent) luminous efficiency and reduced power consumption and having a sufficient thickness of the anode, and a method of preparing the same. An example provides an organic light emitting diode (OLED) comprising: a substrate; a reflective layer on the substrate and comprising a metal; a first electrode on the reflective layer and comprising light transmissive zinc aluminum oxide (AZ0); An organic layer on the first electrode and including an emissive layer; and a second electrode on the organic layer and including a semi-transparent reflective layer. The OLED may further comprise a thin film electrically disposed on the substrate and electrically coupled to the reflective layer The OLED may further include a thin film transistor and a contact layer interposed between the reflective layer and the substrate and including AZO, and wherein the contact layer is connected to the thin film transistor The organic layer may further include a first layer between the emissive layer and the first electrode, wherein the first layer has a thickness in a range of about 4 〇 nm to about 12 〇 nm. A thickness in the range of from about 30 nm to about 14 Å. The light transmissive AZ0 玎 has an absorption constant in the range of from about 1 χ 1 〇 3 to about 2 χ 1 〇 - 2. Another embodiment of the present invention provides an organic light emitting diode. The method of 201038125 (OLED), the method comprising: forming a reflective layer comprising a metal on a substrate; forming a first electrode comprising light-transmissive zinc aluminum oxide (AZ〇) on the reflective layer; forming on the first electrode An organic layer comprising an emissive layer; and forming a second electrode comprising a semi-permeable reflective layer on the organic layer. The forming of the first electrode may include depositing an oxidized chain on the reflective layer; and depositing an oxidized word on the reflective layer. The deposition of the oxidation can be performed in parallel with the deposition of the oxidation. The formation of the first electrode can include depositing alumina and oxidation with a weight ratio of between about 1:99 and about 10:9 Å. The deposition of zinc oxide can be in the range of about l〇〇〇c The method may further comprise forming a thin film transistor on the substrate, wherein the reflective layer is electrically coupled to the thin film transistor. The method may further comprise forming the Az〇 before forming the reflective layer. The contact layer is in contact with the thin film transistor, wherein the reflective layer is on the contact layer. The organic layer may further comprise a first layer between the emissive layer and the first electrode, wherein the first layer has about 40 nm to Thickness in the range of about 120 nm. The first electrode can have a thick sound in the range of about 30 nm to about 140 nm. The first electrode and the reflective layer can be patterned in parallel. Thus, in view of the above and as described in more detail below Although the first electrode formed on the reflective layer of the top emission structure is sufficiently thick, the luminous efficiency of one embodiment of the present invention is not lowered. 201038125 therefore reduces power consumption and, in addition, because the first electrode is thick enough and can also increase OLED efficiency. Further, the resonance thickness of the reflective layer and the second electrode as the semi-transmissive reflective layer can be made thick by the first electrode thickness 4. The first layer of the thickness of the core, rather than the organic layer, can also be increased by the parallel (or simultaneous) reflective layer to increase the productivity of the OLED. The electrode is sufficiently thick and the first embodiment and the accompanying drawings Illustrative embodiments of the invention, together with the specification, are used to illustrate the principles of the invention. In the following embodiments, some illustrative specific examples of the invention are described by way of illustration only. As will be appreciated by those skilled in the art, the specific examples can be modified in a manner that is deviating from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative rather than limiting. Like reference numerals indicate like elements throughout the specification. 1 is a schematic cross-sectional view of an organic light emitting diode (OLED) according to an embodiment of the present invention. Referring to FIG. 1 , an OLED according to an embodiment of the present invention includes a substrate j, a reflective layer 2 formed on the substrate 1, a first electrode 3 formed on the reflective layer 2, and an organic layer formed on the first electrode 3. Layer 4 and a second electrode 5 formed on the organic layer 4. The substrate 1 may be formed of glass, but the material for forming the substrate 1 is not limited thereto. The substrate 1 may also be formed of plastic, metal or the like. An insulating layer may also be formed on the substrate ι (for example between the substrate 1 and the reflective layer 2) to planarize the surface of the substrate 1 with 201038125 and to reduce or prevent the diffusion of impurities from the substrate. The substrate 1 is light transmissive. However, the present invention is not limited thereto, and the substrate 丨 may be opaque. The reflective layer 2 can be formed of a material having a high light reflectivity such as a metal. The thickness of the reflective layer 2 is determined such that the light is sufficiently reflected. The reflective layer 2 may be formed of A, Ag, Cr, M, or the like and may have a thickness of about ι, οοο. The first electrode 3 may be formed on the reflective layer 2 using a light-transmitting aluminum-doped oxidized or oxidized aluminum (Az〇). The first electrode 3 serves as the anode of the 〇LED. €) AZ〇 is formed by mixing alumina (e.g., a12〇3) with zinc oxide (e.g., ZnO) at a specific ratio and depositing a mixture. The formed Az〇 can transmit light. The ratio of alumina to zinc oxide can range from 1:99 to 1 〇:9 〇 (or from about 1;99 to 10.90). The ratio of oxidized to oxidized words can be 2.98 (or about 2:98). If the alumina portion is less than 丄 or greater than 1 〇, the resistance value will increase. In addition, 'Oxide and Zinc Oxide can be deposited in parallel (or ◎ simultaneous) at a temperature ranging from 1 〇〇 to 450 ° C (or from about 100 to about 45 〇r) to form AZ0. Floor. In one embodiment, if the deposition temperature is less than the loot, the quality of the AZO layer is lowered, the transmittance is decreased, and the absorption constant k is increased. In a specific example, if the deposition temperature is greater than 4 $ 〇, the substrate will become $. The absorption constant of the AZO layer may range from 1χ1〇-3 to 2χ1〇_2 (or from about ΐχΐ〇·3 to about 2xl〇 2). When the absorption constant k is decreased, the power consumption is lowered, and thus the luminous efficiency of the top emission is improved. Fig. 2 is a graph showing the relationship between the absorption constant k of the layer (π 201038125 and III) of the specific example of the present invention and the absorption constant k of the conventional ITO layer (I) and the wavelength. Curve II of Figure 2 shows the absorption constant k of the AZO layer when alumina is deposited with the oxidation at a weight ratio of 2:98 at 2 °C. Curve III of Figure 2 shows the absorption constant k of the AZO layer when alumina and zinc oxide are deposited at a weight ratio of 2:98 at 40 CTC. According to curve II, the AZO layer exhibits a low absorption constant in the range of 0.016 to 〇.〇12 in the visible light wavelength region in the range of 450 to 650 nm. According to the curve III, the AZO layer exhibits an even lower absorption constant in the range of 0_002 to 0.006 in the visible light wavelength region. The absorption constants of the two AZO layers are much lower than the absorption constants of the ITO layer (I) in the range of 0.022 to 〇.〇4 in the visible light wavelength region. When the absorption constant is reduced by 90. /. At the time, the power consumption is reduced by about 1%. Therefore, the absorption constant of the AZO layer deposited at 400 ° C is smaller than the absorption constant of the AZO layer deposited at 200 ° C. It is difficult to reduce the absorption constant to less than 1χ1〇-3. Since the enamel layer is etched faster than the ruthenium layer used as a conventional anode, it is easier to pattern the ruthenium layer and the reflection layer 2 in parallel (or simultaneously). That is, when the tantalum layer has a thickness of 200 Å (or about 200 Å), it is difficult to etch the ITO layer in parallel (or simultaneously) with the reflective layer 2 formed using Ag. However, since the AZO layer having a thickness of more than 1000 people (or about 1000 A) has a high etching rate, it is easy to etch the AZ layer and the reflection layer 2 formed using Ag in parallel (or simultaneously). Therefore, the first electrode 3 can have a thickness sufficient, that is, a thickness in the range of 30 to 140 nm (or about 30 to about 140 nm), and thus can reduce power consumption, and can satisfy the resonance thickness, that is, the reflective layer 2 and the first The distance between one electrode 5 is t1. A support layer is usually formed on the organic layer, 201038125 to meet the resonance thickness. However, such additional support layers are not required here. The organic layer 4 includes an emissive layer 42. The first layer 41 is interposed between the emissive layer 42 and the first electrode 3 as a common functional layer. The first layer 41 can be formed by stacking a hole injection layer (HIL) and a hole transport layer (HTL) or selectively stacking one of hil and HTL. The HIL can be formed by a material used to form the HIL using thermal evaporation or spin coating.

The material for forming the HIL may be a phthai 〇 Cyanine compound such as copper ugly or a starburst amine derivative such as TCTA, m-MTDATA and m-MTDAPB.

The HTL can be formed on the HIL by vacuum deposition of 'spin coating, casting, and Langmuir Blodgett (LB) HTL material. Or a similar method, used to form the HTL, can be formed by vacuum deposition to obtain a uniform layer and to reduce or prevent pinhole formation. When the HTL is formed by vacuum deposition, the vacuum deposition conditions may vary depending on the material used to form the HTL, and the conditions of σ vacuum deposition are similar to those for forming the HIL. - mercaptophenyl)-N,N'- The material used to form the HTL· can be ν, νι-bis (3 9 201038125 diphenyl-fluorene, 1-biphenyl)-4,4,-diamine ( TPD) and base)-N,N-_-benylbenzidine (α-NPD), but are not limited thereto.

An emissive layer 42 is then formed on the first layer 41, and a second layer 43 is formed on the emissive layer 42 as another common functional layer. The second layer 43 can be formed by stacking an electron injection layer (EIL) with an electron transport layer (ETL) or selectively stacking one of EIL and ETL. The EIL may be formed of LiF, NaC, CsF, Li2, BaO, Liq or the like. The thickness of the EIL may be in the range of 1 to 100 A (or about 1 to about i 〇〇 A), but is not limited thereto.

Liq ETL can be formed using vacuum deposition or spin coating. The material used to form ετ [may be Alq3, but is not limited thereto. Although the thickness of ETL can be

600 A (or the material of his layer varies.

Between ETL. The material used to form the HBL has high electron transport capability and high 201038125

The free potential of the emitting compound. Used to form Balq, BCP and TPBI, but is not limited to this.

Emissive layer 42 may be formed from a mixture of host material and dopant material, or may be formed independently of host material or dopant material. HBL material can be

The host material may be ginseng (8-carbyl-quinolin) aluminum (Aiq3), 9,1 〇_bis(naphthalen-2-yl)anthracene (AND), 3-tert-butyl·9,1〇•2 (naphthalene_2_yl)蒽

(TBADN), 4,4_bis(2,2-diphenyl-ethlyl-1-yl)_4,4'-dinonylphenyl (DPVBi), 4,4·-bis (2,2-di Phenyl-ethylene-diyl)_4,4,_dimethylphenyl (p-DMDPVBi), third (9,9-diaryl) (tdAF), 2-(9,9'_ snail苐-2 -yl)-9,9'-spirobiguanide (BSDF), 2,7-double (9,9'-spiro double burial-2-yl)-9,9'-spirobiguanide (TSDF) , bis(9,9-diarylfluorene) (BDAF), 4,4'-bis(2,2-diphenyl-ethen-1-yl)_4,4'-di-(t-butyl) Phenyl (p-TDPVBi), 1,3-bis(carbazol-9-yl)benzene (mCP), 1,3,5-parade (taste 11 -9-yl)benzene (tCP), 4, 4 ',4M-gin (carbazol-9-yl)triphenylamine (TcTa), 4,4'-bis(indol-9-yl)biphenyl (CBP), 4,4,-bis(9-咔嗤-2,2,-dimethyl-biphenyl (CBDP), 4,4'-bis(carbazol-9-yl)-9,9-dimethyl-indole (DMFL-CBP), 4, 4'-bis(carbazol-9-yl)-9,9-bis(9-phenyl-9H-carbazole) fluorene (FL-4CBP), 4,4,-bis(carbazol-9-yl) -9,9-Dimethylphenyl-indole (DPFL-CBP), 9,9-bis(9-phenyl-9H-carbazole) (FL-2CBP) or an analog thereof. 11 201038125 The doping material can be 4,4,-bis[4-(di-p-tolylamino)styryl] phenyl (DPAVBl), 9,1 〇-bis(naphthalen-2-yl) fluorene (ADN) , 3-tert-butyl-9,10-di(naphthalen-2-yl)indole (TBadn) or an analogue thereof. r~i

DPAVBi

AND

After the organic layer 4 is formed by the TBADN, the second electrode 5 is formed on the organic layer 4. The second electrode 5 is formed using a low work function metal. Semi-reflective reflection can be achieved by reducing the thickness. The Mg:Ag thin layer may have a thickness within the target perimeter of (10) to A (or from about 100 to about 300 A). Low work function metals such as Al, Au and Cr can also be used. * After forming the second electrode 5, a capping layer can be formed on the second electrode 5. The capping layer 6 can be formed of a transparent organic or inorganic material to transmit light. 12 201038125 • Due to optical resonance, the optical coupling efficiency can be increased by adjusting the distance U between the reflective layer 2 and the second electrode 5 to achieve the emission wavelength of the emission layer 42. Since the first electrode 3 is difficult to have the thickness t3 in the conventional OLED, it is necessary to increase the thickness t2 of the first layer 41 to satisfy the resonance distance u. In the conventional OLED, the thickness t3 of the first electrode 3 is equal to or exceeds that of the person. However, according to an embodiment of the present invention, since AZ is used as the first electrode 3, the thickness 〇 of the first electrode 3 may be sufficiently thick, for example, in the range of % to 140 nm (or about 30 to about 14 〇 nm). And thus the thickness t2 of the first layer 41 of the organic crucible 4 can be reduced. According to an embodiment of the present invention, the thickness t2 of the first layer 41 is in the range of 40 to 12 〇 nm (or about 40 to about 120 nm). When the thickness of the organic layer 4 is decreased by increasing the thickness of the AZ 〇 electrode, the driving voltage is decreased. Small and reduced power consumption. 3 is a cross-sectional view of a 〇LED (eg, a top emitting active matrix OLED) of another embodiment of the present invention. The Q buffer layer 11 is formed on the substrate 1, and a pixel circuit including the thin film transistor 12 is formed on the buffer layer 11. In addition to the thin film transistor 12, the pixel circuit can further include a capacitor, although Fig. 3 only illustrates the thin film transistor 12 as an element constituting the pixel circuit. The thin film transistor 12 formed on the buffer layer 11 can be fabricated as follows. The activation layer 121 is formed on the buffer layer 11 using a semiconductor material. A dummy insulating layer 122 is formed to cover the active layer 12 and a gate electrode 123 is formed on the gate insulating layer 122. An interlayer insulating layer 124 is formed on the gate insulating layer 122 to cover the gate electrode 123. The source electrodes 125 and 13 in contact with the active layer 121 are formed on the interlayer insulating layer 24, 201038125. A planarization layer 13 is formed to cover the thin film transistor 12, and a contact layer η which is in contact with the tantalum electrode 126 of the thin film transistor 12 is formed on the planarization layer 13. The contact layer may be formed using the same material as the az layer used to form the first electrode 3 and may have a thickness of 50 to 15 Å (or about 5 Å to about Å illusion) after formation. In the example, if the thickness of the contact I 31 is too large, the contact resistance between the germanium electrode 126 and the reflective layer 2 may be too high. On the other hand, if the thickness of the contact layer 31 < too small, ohmic contact may not be formed (Ohmic) Contact ) ° and the first electrode 3 is formed on the reflective layer 2 formed on the contact layer 31 on the shot layer 2. As shown in FIG. 3, the contact layer 31, the reflective layer 2 and the first electrode 3 can be stacked by sequentially The AZ0 film, the Ag film, and the AZ film are formed by patterning the films in parallel (or simultaneously). As described above, since the contact layer 31 and the first electrode 3 are formed of the AZ0 film, etching can be performed quickly. The etching is rapidly performed, and thus the contact layer 31 and the first electrode 3 may be parallel (or simultaneously) with the reflective layer 2. After the first electrode 3 is formed, the pixel defining layer 14 is formed using an insulating material. The pixel defining layer 14 is formed in the planarization. Layer 13 to cover the edge (or edge portion) of the first electrode 3 Then, the first layer 41, the emission layer 42, and the second layer 43 are sequentially stacked on the first electrode 3 to form the organic layer 4. In this regard, the first layer 41 and the second layer 43 may be formed as a common layer. On the pixel, the emissive layer 42 can be independently patterned on each pixel. 14 201038125 Next, a second electrode 5 is formed on the organic layer 4 as a semi-transparent reflective layer to cover the pixel. The second electrode 5 can be further formed on the second electrode 5. The present invention is not limited to the specific embodiments disclosed, but is instead intended to cover various modifications and equivalent arrangements thereof. 1 is a schematic cross-sectional view of an organic light emitting diode (OLED) D according to an embodiment of the present invention. FIG. 2 is a graph illustrating an absorption number k of a first electrode of the specific example of the present invention and a conventional ITO. The absorption constant k of the layer is related to the wavelength; and FIG. 3 is a schematic cross-sectional view of the LED of another specific example. [Description of main components] 1 · Substrate

4 reflective layer first electrode organic layer 41: first layer 42: emissive layer 43: second layer U: distance between the reflective layer and the second electrode t2: thickness of the first layer t3: thickness of the first electrode 15 201038125 5: second electrode 6: capping layer 11: buffer layer 12: thin film transistor 121: active layer 122: gate insulating layer 123: gate electrode 124: interlayer insulating layer 125: source electrode 126: germanium electrode 1 3 : planarization layer 14 : pixel defining layer 3 1 : contact layer

Claims (1)

201038125 VII. Patent application scope: 1. An organic light emitting diode (OLED) comprising: a substrate; a reflective layer on the substrate and comprising a metal; and located on the reflective layer and comprising light-transmissive zinc-aluminum oxide (AZO) a first electrode; an organic layer on the first electrode and including an emissive layer; and a second electrode on the organic layer and including a semi-transparent reflective layer. 2. The OLED of claim 1, further comprising a thin film transistor electrically coupled to the substrate and electrically coupled to the reflective layer. 3. The OLED of claim 1, further comprising a thin film transistor and a contact layer interposed between the reflective layer and the substrate and comprising AZ, wherein the contact layer is in contact with the thin film transistor. 4. The OLED of claim 1, wherein the organic layer further comprises a first layer between the emissive layer and the first electrode, wherein the first layer has a thickness in the range of about 40 to about 120 μm Inside. 〇 5. The LED of claim 1 wherein the first electrode has a thickness in the range of from about 30 nm to about 14 Å. 6. The OLED of claim 1, wherein the light transmissive AZO has an absorption constant in a range from about 1 x M to about 2 Å 〇. 7. A method of fabricating an organic light emitting diode (OLED), the method comprising: forming a reflective layer comprising a metal on a substrate; forming a first electrical layer comprising light transmissive aluminum zinc oxide (AZO) on the reflective layer 17 201038125 Forming a getter layer comprising an emissive layer on the first electric; and forming a second electrode comprising a semipermeable reflective layer on the organic layer. 8. If the scope of claim 7 is: The shape includes: an electrode shape depositing alumina on the reflective layer; and depositing zinc oxide on the reflective layer. 〇 9. The method of claim 8, wherein the deposition of the oxidized and the zinc oxide can be performed in parallel. The method 'where the ratio of the weight ratio between the first electrodes; the oxidization of the oxide 10. As s. 8 of the patent application, the inclusion includes about 1:99 and about 1 〇:9 〇 with the zinc oxide. #11. The method of claim 8, wherein the oxidation and the deposition of the zinc oxide are carried out at a temperature of about 10 (rc to about 45 (circle rcs. 12.) The method further includes forming a thin film transistor on the substrate, wherein the reflective layer is electrically coupled to the thin film transistor. The method of claim 12, further comprising: before forming the germanium reflective layer Forming a contact layer comprising AZ0 to contact the thin film transistor, wherein the reflective layer is located on the contact layer. The method of claim 7, wherein the organic layer further comprises the emissive layer and the first a first layer between the electrodes, wherein the first layer has a thickness in the range of from about 40 nm to about 120 nm. 15. The method of claim 7, wherein the first electrode member 18 201038125 has about 30 The method of claim 7, wherein the first electrode and the reflective layer can be patterned in parallel. 8. Pattern: (e.g., page C) 19